Rare earth organic acid salt complex with high far infrared emissivity as well as preparation method and application thereof

Abstract

The invention provides a rare earth organic acid salt complex with high far infrared emissivity and a preparation method and application thereof, the molecular general formula of the rare earth organic acid salt complex is RE (OA-SH) 3 (Phen), RE is a rare earth ion, OA-SH is a functionalized oleic acid ligand, Phen is phenanthroline, and the functionalized oleic acid ligand is 11-mercaptoundecane-9-olefine acid. According to the invention, the ternary complex with a clear structure is successfully constructed through a multi-step reaction. Compared with simple neodymium oleate, the ternary complex has the advantage that the far infrared emissivity can be increased from 0.92 to 0.97.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional materials, and particularly relates to a rare earth organic acid salt complex with high far infrared emissivity and a preparation method and application thereof. BACKGROUND

[0002] At present, mainstream materials for realizing far infrared function include multiple ceramic powders (such as zirconium oxide and aluminum oxide) and some carbon materials. Although these materials have certain far infrared emission capacity, they generally have problems such as low emissivity (usually 0.82-0.88), poor compatibility with organic matrix, high-temperature sintering, and large energy consumption. Although some studies have attempted to introduce rare earth oxides for modification, the physical mixing method is difficult to achieve uniform dispersion at the molecular level, and the performance improvement is limited. Moreover, the rare earth oxides are prone to agglomeration and sedimentation in the organic system, which affects the stability of product performance. It is of great significance to develop a new type of rare earth far infrared material that can be synthesized at room temperature, has good compatibility with organic matter, and has high emissivity. Oleic acid, as a common surfactant, has been used to modify nano-oxides to improve dispersibility, but its direct coordination with rare earth ions and systematic application in constructing high-efficiency and stable far infrared functional materials are still blank. SUMMARY

[0003] Therefore, the present application aims to overcome the defects in the prior art and provides a rare earth organic acid salt complex with high far infrared emissivity and a preparation method and application thereof.

[0004] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows: In a first aspect, the present application provides a rare earth organic acid salt complex with high far infrared emissivity, and the molecular general formula of the rare earth organic acid salt complex is RE(OA-SH)3(Phen), wherein RE is a rare earth ion, OA-SH is a functionalized oleic acid ligand, and Phen is o-phenanthroline. The functionalized oleic acid ligand is 11-mercapto-undec-9-enoic acid.

[0005] The o-phenanthroline (Phen) introduced in the rare earth organic acid salt complex with high far infrared emissivity of the present application serves as an efficient "antenna" or "energy capturer", which has a large conjugated π system and can effectively absorb heat energy or electromagnetic energy in the environment. The functionalized oleic acid (OA-SH) not only coordinates with the rare earth ion through the carboxyl group, but also forms a coordination bond with the rare earth ion through the terminal mercapto group (-SH). This multi-dentate coordination mode cooperates with the o-phenanthroline to "lock" the rare earth ion in a rigid and protected coordination environment, thereby maximally inhibiting the energy non-radiation dissipation (i.e., energy loss in the form of heat) caused by molecular vibration.

[0006] Preferably, the rare earth ion is Nd3+ La 3+ Ce 3+ one or more of Y, La

[0007] Preferably, the preparation method of the functionalized oleic acid ligand comprises the following steps: S1. oleic acid, methanol and concentrated sulfuric acid are added to a reaction vessel, stirred and refluxed at 65-75℃ for 5-7 hours, after the reaction is completed, the reaction mixture is washed with base, washed with water, and dried to obtain methyl oleate; S2. mercaptoacetic acid is dissolved in anhydrous dichloromethane, and thionyl chloride is added dropwise to react, and after the reaction is completed, an acyl chloride intermediate is obtained, then allyl alcohol and a basic catalyst are added, and after reaction, washing and drying, mercaptoacetic acid allyl ester is obtained; S3. methyl oleate, mercaptoacetic acid allyl ester and a photoinitiator are dissolved in toluene, and reacted under irradiation of a 365 nm UV lamp for 10-14 hours, then after purification, hydrolysis is carried out by adding a base, and after acidification, precipitation, filtration and drying, the functionalized oleic acid ligand is obtained.

[0008] Preferably, the mass ratio of oleic acid, alcohol solvent and acidic catalyst in step S1 is (90-110):(100-120):(2-5).

[0009] Preferably, the mass ratio of mercaptoacetic acid, acylating agent, allyl alcohol and basic catalyst in step S2 is (90-110):(115-135):(0.3-0.7):(110-125).

[0010] Preferably, the mass ratio of methyl oleate, mercaptoacetic acid allyl ester, photoinitiator and base is (90-110):(40-50):(65-75):(15-25).

[0011] Preferably, the basic catalyst is selected from one or more of triethylamine, N,N-diisopropylethylamine (DIPEA), 4-dimethylaminopyridine (DMAP).

[0012] Preferably, the photoinitiator is selected from one or more of benzoin dimethyl ether, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-2-phenylacetophenone, methyl benzoylformate.

[0013] Preferably, the base is selected from one or more of sodium hydroxide, potassium hydroxide, potassium carbonate.

[0014] In a second aspect, the present application also provides a preparation method of the above-mentioned rare earth organic acid salt complex, comprising the following steps: a. Dissolve the functionalized oleic acid ligand and the rare earth salt in organic solvents respectively, slowly drop the solution of the rare earth salt into the solution of the functionalized oleic acid ligand, and react at 55-65°C for 1.5-2.5 hours to obtain a pre-ligating product; b. Add the o-phenanthroline solution into the pre-ligating product, and reflux at 75-80°C for 5-7 hours; c. Concentrate the reaction solution, precipitate with n-hexane, filter and wash, purify in a Soxhlet extractor for 20-28 hours, and vacuum dry to obtain the final product, a rare earth organic acid salt complex.

[0015] Preferably, the mass ratio of the functionalized oleic acid ligand, the rare earth salt and the o-phenanthroline is (90-110):(30-40):(15-25).

[0016] Preferably, the rare earth salt is selected from one or more of neodymium chloride or its hydrate, cerium chloride or its hydrate, and lanthanum chloride or its hydrate.

[0017] In a third aspect, the present application also provides an application of the above-mentioned rare earth organic acid salt complex as a heat radiation source in physiotherapy, health care, energy saving and environmental protection.

[0018] Compared with the prior art, the present application has the following advantages: (1) The present application aims to protect the carboxyl end and functionalize the alkyl chain end of the oleic acid ligand through fine molecular design, introduce strong coordination ability of sulfhydryl (-SH), and then construct a ternary complex with stable structure and efficient intramolecular energy transfer through multi-step reaction of the rare earth ion and the small molecule second ligand (such as o-phenanthroline), so as to realize the significant improvement of far infrared emissivity and the diversification of functions; (2) The present application successfully constructs a ternary complex with a clear structure. Compared with simple neodymium oleate, the far infrared emissivity of the ternary complex can be improved from 0.92 to 0.97. In addition, due to the "antenna effect" of o-phenanthroline and the introduction of sulfhydryl, the intramolecular energy transfer path is optimized, realizing the synergistic function of far infrared radiation and photothermal therapy. The long-term dispersion stability in the polyurethane matrix is more than 180 days. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The Fourier infrared spectrum of the product prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0020] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0021] In the present text, unless otherwise defined, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0022] In the present text, where values are described as ranges, it is to be understood that the disclosure includes disclosure of all possible sub-ranges within the range, and specific numerical values falling within the range, regardless of whether the specific numerical values or the specific sub-ranges are explicitly stated.

[0023] In the present text, the term "a plurality of" and the like refers to two or more, unless otherwise indicated. For example, "one or more" means one or more than one.

[0024] In the present text, the terms "preferably", "more preferably" and the like are used to describe advantageous embodiments or examples, and should not be construed to limit the scope of the present application.

[0025] In the present text, the term "further" and the like are used for descriptive purposes, and should not be construed to limit the scope of the present application.

[0026] In the present text, the term "and / or" is used to describe the relationship between objects, and means that there can be three relationships. For example, A and / or B means that there are three relationships: A or B, or A and B.

[0027] In the present text, the term "about" means + / - 10% of the specified value, preferably + / - 5%, and more preferably + / - 1%.

[0028] In the present text, the terms "comprising", "including", "having", "containing" and the like are open-ended terms, i.e. meaning "including, but not limited to".

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application.

[0030] The present application will be described in detail below with reference to the examples.

[0031] Example 1 Step 1: Synthesis of functional ligand OA-SH (11-mercapto undec-9-enoic acid) (1) Preparation of methyl oleate (carboxyl protection) In a 250 mL round bottom flask, oleic acid (50 g), methanol (55 g) and catalytic amount of concentrated sulfuric acid (1.5 g) were added. The reaction was stirred at 70 °C for 6 hours (TLC monitoring) with a reflux device. After the reaction was completed, the mixture was poured into a separatory funnel and washed with saturated sodium bicarbonate solution until neutral, and then washed once with saturated brine. The organic phase was separated and dried over anhydrous magnesium sulfate overnight. After filtration, the excess methanol was removed by rotary evaporation to give methyl oleate as a colorless oil, which was used directly in the next step. This step protected the carboxyl group by esterification to avoid interference in the following steps.

[0032] (2) Synthesis of allyl mercaptoacetate In another dry 250 mL three-necked flask, mercaptoacetic acid (50 g) and anhydrous dichloromethane (100 mL) were added. Under ice-water bath cooling and stirring, a mixture of thionyl chloride (60 g) and 20 mL dichloromethane was added dropwise, controlling the temperature below 20 °C. After the addition was completed, it was stirred at room temperature for 2 hours. Subsequently, unreacted thionyl chloride and solvent were completely removed by rotary evaporation to give a light yellow liquid, which was the acyl chloride intermediate without further purification. The acyl chloride intermediate was redissolved in 100 mL dichloromethane, and a mixture of propenol (0.25 g) and triethylamine (60 g) was added slowly under ice-water bath cooling. After natural temperature rise to room temperature, it was stirred for 4 hours. After the reaction was completed, the organic phase was washed with 5% hydrochloric acid, saturated sodium bicarbonate solution and saturated brine in turn. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation after filtration to give allyl mercaptoacetate.

[0033] (3) "Thiol-ene" click chemistry reaction and deprotection Methyl oleate (50 g) obtained in the first step, allyl mercaptoacetate (22.5 g) synthesized in the second step and photoinitiator benzoin dimethyl ether (35 g) were dissolved in 100 mL toluene. After purging oxygen with nitrogen, the reaction mixture was irradiated with a 365 nm UV lamp and stirred at room temperature for 12 hours. After the reaction was completed, toluene was removed by rotary evaporation. The intermediate product was obtained by column chromatography (petroleum ether: ethyl acetate = 10:1). The intermediate product was dissolved in methanol, and sodium hydroxide (10 g) was added. Hydrolysis was carried out by refluxing for 2 hours to remove the protection of carboxyl group and acetyl protection of mercapto group at the same time. After the reaction solution was cooled, the pH was adjusted to 2-3 with dilute hydrochloric acid, and a white precipitate was separated out. The precipitate was filtered and washed with cold water, and dried in vacuum to give the final functional ligand OA-SH (white solid).

[0034] Step two: construction of ternary complex Nd(OA-SH)3(Phen) (1) Pre-ligand reaction Take OA-SH (10.5 g) dissolved in 30 mL of anhydrous ethanol, and place it in a 100 mL three-necked flask. Take neodymium chloride hexahydrate (NdCl3·6H2O) (3.6 g) dissolved in 10 mL of anhydrous ethanol, and slowly drop it into the OA-SH solution through a constant pressure dropping funnel under the protection of nitrogen, and control the temperature to be 60°C. After the dropping is completed, continue to stir the reaction at this temperature for 2 hours, and the solution becomes a light blue transparent liquid.

[0035] (2) Introducing the second ligand Dissolve o-phenanthroline (Phen) (2.0 g) in 10 mL of hot anhydrous ethanol, and then slowly drop it into the above pre-ligating solution. Increase the temperature of the reaction system to 78°C to reflux, and continue to react for 6 hours. During this period, the color of the solution gradually deepens to a deep purple color.

[0036] (3) Purification and drying After the reflux is completed, remove the heat source, and let the reaction liquid naturally cool to room temperature. Then use a rotary evaporator to distill under reduced pressure, and remove most of the solvent to obtain a viscous substance. Add 30 mL of n-hexane to the viscous substance, and after ultrasonic treatment, place it in an ice water bath and stand for 2 hours to allow the product to be eluted. Use suction filtration, and wash the precipitate with a cold n-hexane / ether mixed solvent (v / v=1:1) for 3 times. Transfer the solid product to a Soxhlet extractor, and continuously extract it with anhydrous ether for 24 hours to completely remove the unreacted raw materials. Finally, dry the product at 50°C under vacuum for 12 hours to obtain 0.92 g of a deep purple, metallic luster solid powder, which is the target ternary complex Nd(OA-SH)3(Phen), and the yield is about 85%.

[0037] The Fourier infrared spectrum of the prepared product is shown in Figure 1 , and it can be seen that the ternary complex is successfully prepared according to the present application. In the figure, the characteristic peaks of the free carboxyl group (~1721 cm -1 ) and the free thiol group (~2550 cm -1 ) disappear, and new peaks belonging to the asymmetric and symmetric stretching vibrations of the carboxylate group appear at ~1556 cm -1 and ~1405 cm -1 , which proves the coordination of the carboxyl group with Nd 3+ . The characteristic absorption peak of the Nd-O bond appears at ~506 cm -1 .

[0038] Example 2 Step one: Synthesis of functional ligand OA-SH (11-mercapto undec-9-enoic acid) (1) Preparation of methyl oleate (carboxyl protection) In a 250 mL round bottom flask, add oleic acid (45 g), methanol (50 g) and catalytic amount of concentrated sulfuric acid (1 g). Set up a reflux apparatus and stir the reaction at 70 °C for 6 hours (TLC monitor the reaction completion). After the reaction is completed, pour the mixture into a separatory funnel and wash it carefully to neutral with saturated sodium bicarbonate solution, and then wash it once with saturated brine. Separate the organic phase and dry it over anhydrous magnesium sulfate overnight. After filtration, remove the excess methanol by rotary evaporation to obtain methyl oleate as a colorless oil, which is used directly in the next step. This step protects the carboxyl group by esterification to avoid interference in the subsequent steps.

[0039] (2) Synthesis of allyl mercaptoacetate In another dry 250 mL three-necked flask, add mercaptoacetic acid (45 g) and anhydrous dichloromethane (100 mL). Slowly add a mixture of thionyl chloride (57.5 g) and 20 mL dichloromethane dropwise under ice-water bath cooling and stirring, control the temperature below 20 °C. After the dropwise addition is completed, stir at room temperature for 2 hours. Then, remove the unreacted thionyl chloride and solvent completely by rotary evaporation to obtain a light yellow liquid, which is the acyl chloride intermediate without further purification. Redissolve the acyl chloride intermediate in 100 mL dichloromethane, and slowly add a mixture of propenol (0.15 g) and triethylamine (55 g) under ice-water bath cooling. After natural temperature rise to room temperature, stir for 4 hours. After the reaction is completed, wash the organic phase with 5% hydrochloric acid, saturated sodium bicarbonate solution and saturated brine in turn. Dry the organic phase with anhydrous sodium sulfate, filter and remove the solvent by rotary evaporation to obtain allyl mercaptoacetate.

[0040] (3) "Thiol-ene" click chemistry reaction and deprotection Dissolve the methyl oleate (45 g) obtained in the first step, the allyl mercaptoacetate (20 g) synthesized in the second step and the photoinitiator 2,2-dimethoxy-2-phenylacetophenone (32.5 g) in 100 mL toluene. After purging oxygen with nitrogen, irradiate the reaction mixture with a 365 nm UV lamp and stir at room temperature for 12 hours. After the reaction is completed, remove the toluene by rotary evaporation. Purify by column chromatography (petroleum ether: ethyl acetate = 10:1) to obtain the intermediate product. Dissolve the intermediate product in methanol, add potassium hydroxide (7.5 g) and reflux for 2 hours to perform hydrolysis to simultaneously remove the protection of the carboxyl group and the acetyl protection of the mercapto group. After the reaction solution is cooled, adjust the pH to 2-3 with dilute hydrochloric acid, and a white precipitate is precipitated. Filter, wash the precipitate with cold water and dry in vacuum to obtain the final functional ligand OA-SH (white solid).

[0041] Step two: construction of ternary complex Nd(OA-SH)3(Phen) (1) Pre-ligand reaction Take OA-SH (9 g) dissolved in 30 mL of anhydrous ethanol and place it in a 100 mL three-necked flask. Weigh 3 g of cerium chloride heptahydrate (CeCl3·7H2O) dissolved in 10 mL of anhydrous ethanol, and slowly add it to the OA-SH solution through a constant-pressure dropping funnel under nitrogen protection, controlling the temperature at 60°C. After the addition is complete, continue stirring the reaction at this temperature for 2 hours, and the solution turns into a light blue transparent liquid.

[0042] (2) Introduce the second ligand Dissolve 1.5 g of phenanthroline (Phen) in 10 mL of hot anhydrous ethanol, and then slowly add it to the above pre-ligand solution. Heat the reaction system to 78°C and reflux for 6 hours. During this period, the solution color gradually deepens to a deep purple.

[0043] (3) Purification and drying After the reflux is complete, remove the heat source and let the reaction liquid cool naturally to room temperature. Then use a rotary evaporator to distill under reduced pressure to remove most of the solvent, obtaining a sticky substance. Add 30 mL of n-hexane to the sticky substance, sonicate it, and then place it in an ice water bath for 2 hours to allow the product to be fully analyzed and precipitated. Use a suction filter to wash the precipitate with a cold n-hexane / ether mixed solvent (v / v=1:1) three times. Transfer the solid product to a Soxhlet extractor and continuously extract it with anhydrous ether for 24 hours to completely remove the unreacted raw materials. Finally, dry the product at 50°C under vacuum for 12 hours to obtain 0.92 g of a deep purple, metallic luster solid powder, which is the target ternary complex Nd(OA-SH)3(Phen).

[0044] Example 3 Step one: Synthesis of functional ligand OA-SH (11-mercapto-undec-9-enoic acid) (1) Preparation of methyl oleate (carboxyl protection) In a 250 mL round-bottom flask, add oleic acid (55 g), methanol (60 g), and a catalytic amount of concentrated sulfuric acid (2.5 g). Build a reflux device and stir the reaction at 70°C for 6 hours (TLC monitoring reaction completion). After the reaction is complete, pour the mixture into a separatory funnel, wash it carefully to neutral with saturated sodium bicarbonate solution, and then wash it once with saturated brine. Separate the organic phase and dry it with anhydrous magnesium sulfate overnight. After filtration, remove the excess methanol by rotary evaporation to obtain colorless oily methyl oleate, which is directly used in the next step. This step protects the carboxyl group through esterification to avoid interference in the subsequent steps.

[0045] (2) Synthesis of mercaptoacetic acid allyl ester A dry 250 mL three-necked flask was charged with mercaptoacetic acid (55 g) and anhydrous dichloromethane (100 mL). A solution of thionyl chloride (67.5 g) in 20 mL dichloromethane was added dropwise under ice-water cooling and stirring, controlling the temperature below 20 °C. After the addition was completed, the reaction was stirred at room temperature for 2 h. Subsequently, unreacted thionyl chloride and solvent were removed by rotary evaporation to give a light yellow liquid, which was the acyl chloride intermediate without further purification. The acyl chloride intermediate was redissolved in 100 mL dichloromethane, and a mixture of allyl alcohol (0.35 g) and triethylamine (62.5 g) was added dropwise under ice-water cooling. After the temperature was allowed to rise to room temperature, the reaction was stirred for 4 h. After the reaction was completed, the organic phase was washed successively with 5% hydrochloric acid, saturated sodium bicarbonate solution and saturated brine. The organic phase was dried over anhydrous sodium sulfate, filtered and the solvent was removed by rotary evaporation to give allyl mercaptoacetate.

[0046] (3) Thiol-ene click chemistry reaction and deprotection Methyl oleate (55 g) obtained in the first step, allyl mercaptoacetate (25 g) synthesized in the second step and photoinitiator methyl benzoylformate (37.5 g) were dissolved in 100 mL toluene. After the oxygen was removed by nitrogen purging, the reaction mixture was irradiated with a 365 nm UV lamp and stirred at room temperature for 12 h. After the reaction was completed, toluene was removed by rotary evaporation. The intermediate was purified by column chromatography (petroleum ether: ethyl acetate = 10: 1) to give the intermediate. The intermediate was dissolved in methanol, and potassium carbonate (12.5 g) was added. The reaction was carried out by refluxing for 2 h to hydrolyze and remove the protection of carboxyl and acetyl of mercapto at the same time. After the reaction solution was cooled, the pH was adjusted to 2-3 with dilute hydrochloric acid, and white precipitate was separated out. The precipitate was filtered and washed with cold water, and dried in vacuum to give the final functional ligand OA-SH (white solid).

[0047] Step two: construction of ternary complex Nd(OA-SH)3(Phen) (1) pre-ligating reaction OA-SH (11 g) was dissolved in 30 mL anhydrous ethanol in a 100 mL three-necked flask. Lanthanum chloride hexahydrate (LaCl3·6H2O) (4 g) was weighed and dissolved in 10 mL anhydrous ethanol, and then slowly added dropwise to the OA-SH solution through a constant pressure dropping funnel under nitrogen protection, controlling the temperature at 60 °C. After the addition was completed, the reaction was continued to stir at this temperature for 2 h, and the solution turned into a light blue transparent liquid.

[0048] (2) introduction of the second ligand Phenanthroline (Phen) (2.5 g) was dissolved in 10 mL hot anhydrous ethanol, and then slowly added dropwise to the above pre-ligating solution. The reaction system was heated to 78 °C to reflux, and the reaction was continued for 6 h. During this period, the color of the solution gradually deepened to deep purple.

[0049] (3) Purification and drying After reflux, the heat source was removed, and the reaction solution was allowed to cool naturally to room temperature. Subsequently, vacuum distillation was performed using a rotary evaporator to remove most of the solvent, yielding a viscous substance. 30 mL of n-hexane was added to the viscous substance, and after sonication, the mixture was placed in an ice-water bath and allowed to stand for 2 hours to allow the product to fully precipitate. The precipitate was filtered and washed three times with a cold n-hexane / diethyl ether mixture (v / v = 1:1). The solid product was transferred to a Soxhlet extractor and continuously extracted with anhydrous diethyl ether for 24 hours to completely remove unreacted starting materials. Finally, the product was vacuum dried at 50°C for 12 hours to obtain 0.92 g of a deep purple, metallic-lustered solid powder, which is the target ternary complex Nd(OA-SH)3(Phen).

[0050] Comparative Example 1 Compared with Example 1, this comparative example omits the "thiol-ene" click chemistry reaction step in the synthesis of the functionalized ligand OA-SH, and directly uses unfunctionalized oleic acid as the ligand. All other steps are the same.

[0051] Comparative Example 2 Compared with Example 1, this comparative example omits the second ligand o-phenanthroline in the construction of the ternary complex, and only synthesizes the binary complex. All other steps are the same.

[0052] The rare earth organic acid salt complexes prepared in the examples and comparative examples were subjected to far-infrared emissivity and stability tests, wherein: The test method for far-infrared emissivity is as follows: the powder material to be tested is pressed into a sheet sample with a flat surface and uniform thickness under a pressure of 15 MPa. The prepared sample and a standard blackbody source are placed in the measurement optical path of the instrument. At room temperature, the infrared spectra of the sample and the blackbody source in a specific wavelength band are measured respectively. By comparing the spectral radiation signal of the sample with the spectral radiation signal of an ideal blackbody at the same temperature, the far-infrared emissivity (8-14 μm) of the sample in the normal direction is calculated.

[0053] The stability test method is as follows: Mix the powder with deionized water at a ratio of 1:3 and disperse evenly. Add dispersant and stir. Take a small amount of liquid into a crucible and weigh its initial mass. Bake at 700℃ for 1 hour and test the remaining mass. The remaining mass / initial mass is the solid content. Test the solid content every 5 days. When the solid content decreases by 10%, the dispersion stability is considered to have decreased significantly.

[0054] The measurement results are shown in the table below:

[0055] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A rare earth organic acid salt complex having a high far infrared emissivity, characterized by: The molecular general formula of the rare earth organic acid salt complex is RE(OA-SH)3(Phen), wherein RE is a rare earth ion, OA-SH is a functionalized oleic acid ligand, and Phen is o-phenanthroline, and the functionalized oleic acid ligand is 11-mercapto-undec-9-enoic acid.

2. The rare earth organic acid salt complex having high far infrared emissivity according to claim 1, characterized by: The rare earth ions are one or more of Nd 3+ , La 3+ , Ce 3+ .

3. The rare earth organic acid salt complex having high far infrared emissivity according to claim 1, characterized by: The preparation method of the functionalized oleic acid ligand comprises the following steps: S1. oleic acid, methanol and concentrated sulfuric acid are added to a reaction container, and stirred and refluxed at 65-75 DEG C for 5-7 hours, after the reaction is completed, the reaction product is washed with alkali, washed with water, and dried to obtain methyl oleate; S2. mercaptoacetic acid is dissolved in anhydrous dichloromethane, and thionyl chloride is added dropwise to react, after the reaction is completed, an acyl chloride intermediate is obtained, then allyl alcohol and an alkaline catalyst are added, and after reaction, washing and drying, mercaptoacetic acid allyl ester is obtained; S3. methyl oleate, mercaptoacetic acid allyl ester and a photoinitiator are dissolved in toluene, and reacted under irradiation of a 365 nm UV lamp for 10-14 hours, after purification, hydrolysis is carried out by adding alkali, and the functionalized oleic acid ligand is obtained after acidification, precipitation, filtration and drying.

4. The rare earth organic acid salt complex having high far infrared emissivity according to claim 3, characterized by: The mass ratio of the oleic acid, methanol and concentrated sulfuric acid in step S1 is (90-110):(100-120):(2-5).

5. The rare earth organic acid salt complex having high far infrared emissivity according to claim 3, characterized by: The mass ratio of the mercaptoacetic acid, thionyl chloride, allyl alcohol and alkaline catalyst in step S2 is (90-110):(115-135):(0.3-0.7):(110-125).

6. The rare earth organic acid salt complex having high far infrared emissivity according to claim 3, characterized by: The mass ratio of the methyl oleate, mercaptoacetic acid allyl ester, photoinitiator and alkali is (90-110):(40-50):(65-75):(15-25).

7. The rare earth organic acid salt complex with high far infrared emissivity according to claim 3, characterized in that: The alkaline catalyst is selected from one or more of triethylamine, N,N-diisopropylethylamine and 4-dimethylaminopyridine; The photoinitiator is selected from one or more of benzpinacol, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-2-phenylacetophenone and methyl benzoylformate; The alkali is selected from one or more of sodium hydroxide, potassium hydroxide and potassium carbonate.

8. A method for producing the rare earth organic acid salt complex as claimed in any one of claims 1 to 7, characterized by: The method comprises the following steps: a. the functionalized oleic acid ligand and the rare earth salt are respectively dissolved in an organic solvent, the rare earth salt solution is slowly added dropwise into the functionalized oleic acid ligand solution, and the pre-ligating product is obtained after reaction at 55-65 DEG C for 1.5-2.5 hours; b. the o-phenanthroline solution is added into the pre-ligating product, and the reaction is carried out at 75-80 DEG C for 5-7 hours; c. the reaction liquid is concentrated, precipitated with n-hexane, filtered and washed, and the final product, the rare earth organic acid salt complex, is obtained after purification with a Soxhlet extractor for 20-28 hours and vacuum drying.

9. The method of claim 8, wherein the method is characterized by: The mass ratio of the functionalized oleic acid ligand, the rare earth salt and the o-phenanthroline is (90-110):(30-40):(15-25), and the rare earth salt is selected from one or more of neodymium chloride or its hydrate, cerium chloride or its hydrate and lanthanum chloride or its hydrate.

10. Application of the rare earth organic acid salt complex according to any one of claims 1-7 as a heat radiation source in physiotherapy, health care, energy saving and environmental protection.

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